<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <link rel="stylesheet" href="../css/reset.css">
    <style>
        .a {
            float: left;
            line-height: 40px;
            border-bottom: 1px solid #000;
            margin: 10px;
        }

        .b {
            float: left;
            line-height: 40px;
            border-bottom: 1px solid #000;
            margin: 10px;
            padding: 0 10px;
        }

        .c {
            float: left;
            line-height: 40px;
            margin: 10px;
            position: relative;
        }

        .c::after {
            content: "";
            width: 10px;
            height: 1px;
            background-color: #f00;
            position: absolute;
            bottom: 0;

            left: 50%;
            transform: translateX(-50%);
        }



        .d {
            width: 100px;
            height: 100px;
            float: left;
            margin: 10px;
            position: relative;
            background-color: #ff0;
        }

        .d::after {
            content: "";
            width: 90px;
            height: 1px;
            background-color: #f00;
            position: absolute;
            top: 0;
            left: 5px;
        }

        .d::before {
            content: "";
            width: 1px;
            height: 90px;
            background-color: #f00;
            position: absolute;
            left: 0;
            top: 5px;
        }
    </style>
</head>

<body>

    <div class="a">1111</div>


    <div class="b">1111</div>

    <div class="c">111111111111111111111</div>


    <div class="d"></div>
    <div class="d"></div>
    <div class="d"></div>

</body>

</html>